1. Field of the Invention
The present invention relates generally to acoustical sensing devices, and more specifically, to a small palm-held acoustical sensing device for engine diagnostic applications.
2. Background of the Invention
Acoustical sensing devices have been in use for some time for diagnosing engine problems in automotive and other engines. Mechanical failure is generally preceded by operating conditions that generate various noises (e.g., bearing squeal or knocking from loose parts) that can be detected if a sensing device is acoustically coupled to the noise source.
U.S. Pat. No. 5,445,026 xe2x80x9cELECTRONIC INSTRUMENT FOR LOCATING AND DIAGNOSING ENGINE SOUNDSxe2x80x9d, issued to the inventor of the present invention, describes a first acoustical sensing device having a flexible arm that may be directed toward a noise source within an engine compartment. U.S. Pat. No. 5,435,185 xe2x80x9cELECTRONIC INSTRUMENT FOR LOCATING AND DIAGNOSING AUTOMOTIVE CHASSIS SOUNDSxe2x80x9d, also issued to the inventor of the present invention, describes a second acoustical sensing device mounted on a clamp and connected via a flexible cable. The first device is useful for quickly scanning reachable engine components and the second device is useful for more permanently attaching a sensor where the first device cannot reach, or where it is desirable to leave the sensor in place for a longer period of time while adjustments are made, for consultation or in order to maintain precise placement of the sensor.
The first (flexible arm) device uses a sensing element that has wide bandwidth for the best sensitivity to the spectrum of noises available. The second (clamping) device uses a sensing element that is durable and easily coupled to the clamping device but has a narrow bandwidth. Both devices are useful for different purposes, as the second device can access locations in an engine compartment that the first cannot, and the first device is sensitive to noises that the second device cannot detect. In particular, it has been noticed that a lower bandwidth can exclude normal engine noise, leaving the operator no level of reference to determine the relative level (and hence importance) of a noise detected by the sensing device.
Therefore, it would be desirable to provide a single low-cost device incorporating the advantages of a clamping device and a device with a flexible shaft. It would be further desirable to provide a clamping device with a wider bandwidth. It would also be desirable to provide a flexible shaft device that improves access to engine compartment locations.
The above objectives of providing a single low cost device having clamping and flexible shaft device advantages, a clamping device with wider bandwidth and a flexible shaft device with improved access are accomplished in various apparatus in accordance with embodiments of the present invention. A palm-held housing incorporates an amplifier, batteries and volume control, along with an audio jack for connection of headphones and may include one or more input jacks for detachably coupling flexible shaft or clamping sensors. The housing is adapted to fit within the palm of a hand, so that the effective reach of the device with a flexible shaft is greater than the reach of the user""s fingers. The clamping device incorporates a condenser microphone coupled to the clamp with an air-tight seal to provide enhanced bandwidth and sensitivity.
The foregoing and other objectives, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.